A combined immunological and biochemical approach is used to elucidate the pathogenesis and etiology of Huntington's chorea and to discover a potential diagnostic marker for the asymptomatic carrier of the disease. Spinal fluid and serum are assessed for mutant proteins using two-dimensional gel electrophoresis with silver staining, and for antineuronal antibodies and immune complexes using Raji cell assays. Lymphocyte cells are analyzed for differences in membrane structural proteins. A variety of lymphocyte subpopulations from patients with Huntington's disease are compared with those from normal subjects.